The invention relates to a rotatably drivable cutting tool, for example, a fine machining tool such as a reamer.
Such tools must meet a wide variety of demands. On the one hand, increasingly higher machining accuracy is demanded of such tools, which requires a high dimensional accuracy of the blade positioning and a high stability during dynamic loading of the blades and shank. On the other hand, an increasingly longer service life is demanded of such tools, for which reason a coolant/lubricant supply system is regularly integrated in such tools. This coolant/lubricant supply system which is integrated in the tool is intended to ensure that the most loaded regions of the tool receive a sufficient supply of coolant/lubricant at any time during use.
There are various approaches in the prior art for designing generic tools with integrated coolant/lubricant supply systems.
The document DE 10347755 A1 discloses a generic tool configured as a high-speed reamer, in which a cutting head, which is connected in a rotationally and axially fixed manner to a shank part and can be fabricated from a hard material such as a sintered material, is supplied with coolant/lubricant by means of a central coolant/lubricant supply channel in the tool shank and a radial channel system in or at the interface to the cutting head. The radially outer mouth openings of the radial channel system are covered by a coolant-conducting sleeve which extends in the direction of the tool tip as far as a runout region of the flutes and can thus ensure that the supplied coolant/lubricant can be fed into the flutes with minimal losses.
This known coolant/lubricant supply system which is integrated into the shank tool is also suitable for what is known as MQL (Minimal Quantity Lubrication) technology, according to which the coolant/lubricant—in contrast to “wet machining”—is guided to the blades in a compressed air flow in an extremely low concentration. The lubricating medium is therefore supplied to the blades as an aerosol during machining, with the aim of producing a sufficient lubricating film in the direct vicinity of the cutting edges.
With MQL technology it is however necessary to conduct the lubricant to the blades in a precise dosage and as constant a concentration as possible. In order to achieve this object while at the same time reducing the fabrication outlay for producing the tool, the document DE 202004008566 U1 describes a high-speed reamer in which a sleeve on the chucking section extends as far as the flute runout region of the tool, wherein the sleeve is configured in one piece with the chucking section and receives the reamer shank in the interior in order to form axial coolant/lubricant channels. The lubricant channels which extend axially are supplied by a central lubricant channel in the chucking section in such a manner that the cooling channel has a constant cross section from the shank end as far as the flute runout region.
In the two known cases, the supply of the blades with coolant/lubricant can only be achieved by a correspondingly high outlay on the production of the tool. Furthermore, the known tools must be assembled from different components.